🗊Презентация Line protection

LINE PROTECTION

Faults “Faults come uninvited and seldom go away voluntarily.”  Fault Types: ●Single line-to-ground Line-to-line Three Phase Line-to-line-to-ground

HOW DO WE DO PROTECT Transmission Lines? Overcurrent Directional overcurrent Distance Pilot Line Current Differential

Assignment of relay protection of power transmission line In the event of damage to the insulation of the cable anywhere or extended overhead line voltage is applied to the line creates a leakage current or a short circuit through the broken section. The causes insulation failure can be a variety of factors that can exclude himself or to continue their devastating effects. For example, flying between the wires overhead line Stork created a phase to phase fault with their wings and burned, falling nearby.

Principles of relay protection Supervision network status To monitor the electrical parameters of power lines need to have bodies of their measurements, which are able to continuously monitor all of the normal mode rejection in the network and at the same time meet the requirements for safe operation. The power lines of all voltages, this function is assigned to the measuring transformers. They are divided into transformers: • Current (CURRENT TRANSFORMERS); • voltage (VOLTAGE TRANSFORMERS). Since the quality of protection is of paramount importance for the reliability of the electrical system, by measuring current and voltage transformers are increased requirements for accuracy of which are determined by their metrological characteristics. Accuracy classes of measuring transformers for use in devices RZA (relay protection and automation) are normalized values ​​of "0.5", "0.2" and "P".

MEASURING TRANSFORMERS

Processing the information received organs In relaying the main operating element is a switch - electrical device that performs two main functions: • monitors the quality of the controlled parameter, such as current and normally supports stable and does not change the state of its contact system; • If a critical value, called the set point or the minimum threshold, instantly switches the position of the contacts and in this state as long as the monitoring value will not return to normal values. The principles of the relay switching schemes of current and voltage in the secondary circuit helps to understand representation of sinusoidal harmonic vector quantities with the image of the complex plane.

Examples of expressions of sinusoidal harmonics of the vector unit circle

Resistance line control methods relay protection devices, estimating the distance to the short circuit has arisen on the basis of measuring the electrical resistance, called spacers or abbreviated DMZ defenses. They are also used in the work circuit current and voltage transformers. To measure the resistance of the expression is used Ohm's Law, described for the section of the circuit concerned. When passing through the active sinusoidal current, capacitive and inductive impedance vector of the voltage drop across them is deflected in different directions. It takes into account the behavior of relay protection.

BEHAVIOUR current vector and the voltage on various kinds RESISTANCE

Basic protection of high-voltage lines (differential-phase protection type DFP-201) Differential - phase protection type DFP-201 is used as the main protection of overhead transmission lines with voltage of 110 - 220 kW, which is necessary to disable all kinds of damage without delay short-circuit at any point of the protected line. The basis of the protection actions laid differential principle or the comparison phase currents at opposite ends of the line. Unlike conventional differential protection, diffaznye protection can protect objects much greater extent (hundreds of kilometers). Protection provides information on the current direction of the object to an object at a high frequency (usually) channel, the main element of which is a transmission line. Some transceivers have a modification for communication over fiber - optic lines (FOL), but widespread, they have not yet received, why restrict ourselves to the high-frequency (HF) communication channels and their elements.

At fault is DFP zone does not work, so it can not be used for remote backup. DFP is not responding to overload, swing, asynchronous course and unbalance in the system. Protection DFP can be used on lines equipped with per phase reclosure (APA) devices. At fault is DFP zone does not work, so it can not be used for remote backup. DFP is not responding to overload, swing, asynchronous course and unbalance in the system. Protection DFP can be used on lines equipped with per phase reclosure (APA) devices. Protection generally consists of two (sometimes three) half-sets. Each of them includes a relay and a high-frequency part. Coverage is limited to protect the current transformers mounted on the ends of the protected line.

Starting authority starts the transmitter with the appearance of faults in the network environment. Starting authority starts the transmitter with the appearance of faults in the network environment. The organ manipulation controls the parameters of the RF signal generated by the transmitter. comparing the current phase Authority (CSFs), according to information received from the receiver determines the short circuit: in the protection of coverage area or beyond. The output relay acts on the circuit breaker (B) The logical part of the protection on the information obtained from the starting body, forms a team to start the RF transmitter, the preparation phase comparison authority to act on the trip and prepares relay output circuit.

Diagram illustrating the operation of the protection in case of short circuit in the action zone and outside it, is given below:

If a short circuit in the protection range (to protect the line A - B) positive half cycle I1 + kI2 conditional current half-sets AB (substation A line in the direction of the substation B) and BA coincide (Figures A1 and B1). Positive (or negative depending on the type of HF post) half-cycle current corresponds to the emergence of high-frequency pulse output UVCHP RF transmitter (c1). Pulses on Ui Rx receiver input from its own transmitter and received from the opposite end of the line are the same or close to the phase (G1). In the absence of receiver Ilim equal to 20 mA current output signal (in some cases - 10 mA), and falls to zero (e1) when a signal. Intermittent reception current through phase comparison transformer body is converted into a pulsating current in the relay coil 2-WP4 (IPR4 e1 diagram). If a short circuit in the protection range (to protect the line A - B) positive half cycle I1 + kI2 conditional current half-sets AB (substation A line in the direction of the substation B) and BA coincide (Figures A1 and B1). Positive (or negative depending on the type of HF post) half-cycle current corresponds to the emergence of high-frequency pulse output UVCHP RF transmitter (c1). Pulses on Ui Rx receiver input from its own transmitter and received from the opposite end of the line are the same or close to the phase (G1). In the absence of receiver Ilim equal to 20 mA current output signal (in some cases - 10 mA), and falls to zero (e1) when a signal. Intermittent reception current through phase comparison transformer body is converted into a pulsating current in the relay coil 2-WP4 (IPR4 e1 diagram). When faults outside the protection coverage (protection line B - B) positive half cycle of the current conditional shifted by about 180 ° (a2, b2). The pulses at the receiver from its own transmitter and received at the opposite end of the line are in antiphase (r2). Receiving current and the coil current is zero 2-4PR (d2, e2).

References http://dororz.ru/ http://electricalschool.info/relay/1647-kak-ustroena-relejjnaja-zashhita-linijj.html